Control of diesel gaseous and particulate emissions with a tube-type wet electrostatic precipitator.
In this study, experiments were performed with a bench-scale tube-type wet electrostatic precipitator (wESPs) to investigate its effectiveness for the removal of mass- and number-based diesel particulate matter (DPM), hydrocarbons (HCs), carbon monoxide (CO), and oxides of nitrogen (NOx) from diesel exhaust emissions. The concentration of ozone (O3) present in the exhaust that underwent a nonthermal plasma treatment process inside the wESP was also measured. A nonroad diesel generator operating at varying load conditions was used as a stationary diesel emission source. The DPM mass analysis was conducted by means of isokinetic sampling and the DPM mass concentration was determined by a gravimetric method. An electrical low-pressure impactor (ELPI) was used to quantify the DPM number concentration. The HC compounds, n-alkanes, and polycyclic aromatic hydrocarbons (PAHs) were collected on a moisture-free quartz filter together with a PUF/XAD/PUF cartridge and extracted in dichloromethane with sonication. Gas chromatography (GC)/mass spectroscopy (MS) was used to determine HC concentrations in the extracted solution. A calibrated gas combustion analyzer (Testo 350) and an O3 analyzer were used for quantifying the inlet and outlet concentrations of CO and NOx (nitric oxide [NO] + nitrogen dioxide [NO2]), and O3 in the diesel exhaust stream. The wESP was capable of removing approximately 67-86% of mass- and number-based DPM at a 100% exhaust volumetric flow rate generated from 0- to 75-kW engine loads. At 75-kW engine load, increasing gas residence time from approximately 0.1 to 0.4 sec led to a significant increase of DPM removal efficiency from approximately 67 to more than 90%. The removal of n-alkanes, 16 PAHs, and CO in the wESP ranged from 31 to 57% and 5 to 38%, respectively. The use of the wESP did not significantly affect NOx concentration in diesel exhaust. The O3 concentration in diesel exhaust was measured to be less than 1 ppm. The main mechanisms responsible for the removal of these pollutants from diesel exhaust are discussed.
Saiyasitpanich
Phirun
P
Department of Civil and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45211-0071, USA.
Keener
Tim C
TC
Lu
Mingming
M
Liang
Fuyan
F
Khang
Soon-Jai
SJ
D000397:Air Pollution / Q000517:prevention & control*; D002248:Carbon Monoxide / Q000032:analysis; D004563:Electrochemistry; D006838:Hydrocarbons / Q000032:analysis; D009589:Nitrogen Oxides / Q000032:analysis; D010126:Ozone / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis*; D001335:Vehicle Emissions / Q000032:analysis*
D006838:Hydrocarbons; D009589:Nitrogen Oxides; D052638:Particulate Matter; D001335:Vehicle Emissions; D010126:Ozone; D002248:Carbon Monoxide